Use of meta-substituted alkyl or alkenyl benzoic acid esters as selective post-emergence crabgrass herbicides

ABSTRACT

ALKYL, CYCLOALKYL, ALKENYL, ALKYNYL, AND HYDROXYALKYL ESTERS OF META-SUBSTITUTED ALKYL OR ALKENYL BENZOIC ACID FORM A NEW CLASS OF SELECTIVE HERBICIDES. THESE META-SUBSTITUTED ALKYL OR ALKENYL BENZOIC ACID ESTERS AND HERBICIDAL COMPOSITIONS CONTAINING THESE ESTERS ARE HIGHLY EFFECTIVE AS POST-EMERGENCE CONTACT CRABGRASS HERBICIDES.

3,681,045 USE OF META-SUBSTITUTED ALKYL R ALKENYL BENZOIC ACID ESTERS AS SELECTIVE POST-EMERGENCE CRAB- GRASS HERBICIDES Stanley T. D. Gough, Raritan, N.J., assignor to Mobil Oil Corporation No Drawing. Filed July 29, 1969, Ser. No. 845,915 Int. Cl. A01n 9/24 US. Cl. 71-107 1 Claim ABSTRACT OF THE DISCLOSURE Alkyl, cycloalkyl, alkenyl, alkynyl, and hydroxyalkyl esters of meta-substituted alkyl or alkenyl benzoic acid form a new class of selective herbicides. These meta-substituted alkyl or alkenyl benzoic acid esters and herbicidal compositions containing these esters are highly efiective as post-emergence contact crabgrass herbicides.

BACKGROUND OF THE INVENTION Field of the invention This invention is directed to the novel use of alkyl, cycloalkyl, alkenyl, alknyl, and hydroxyalkyl esters of meta-substituted alkyl or alkenyl benzoic acid as selective post-emergence crabgrass herbicides.

Description of the prior art In US. Patent 2,848,700, there is disclosed as a herbicide trichlorobenzoic acid for nonselective control of certain undesirable broadleaf Weeds and certain species of Woody plants. US. Pat. 3,013,054 discloses another chlorinated benzoic acid, 3,6-dichloro-o-anisic acid, as a herbicide for annual broadleaf Weeds, seeded small grains, and establishing perennial grasses. Further, atlhough a compound such as disodium methylarsonate (US. 3,317,- 951) is active as a post-emergence contact crabgrass herbicide, our findings are that such a compound is not selective in that regard.

SUMMARY OF THE INVENTION This invention provides the use of selective post-emergence contact crabgrass herbicides of compounds having the structural formula:

wherein R is alkyl (C -C or alkenyl (C -C R is alkyl (C -C5), cycloalkyl (C -C alkenyl (C -C alkynyl (C -C or hydroxyalkyl (C -C5); and in particular where R is alkyl (C -C and R is isoalkyl 3- 5)- DESCRIPTION OF SPECIFIC EMBODIMENTS As will be noted from the formula, the compounds used as selective post-emergence contact crabgrass herbicides in this invention are simple alkyl, cycloalkyl, alkenyl, alkynyl or hydroxyalkyl esters of meta-substituted alkyl or alkenyl benzoic acid. Non-limiting examples of the compounds embodied for use in this invention include: ethyl-m-toluate; n-propyl-m-toluate; isopropyl-m-toluate; n-butyl-m-toluate; isobutyl-m-toluate; t-butyl-m-toluate;

' United States Patent O ice n-pentyl-m-toluate; isopentyl-m-toluate; neopentyl-m-toluate; cyclopropyl-m-toluate; vinyl-m-toluate;

allyl-m-toluate; Z-butyenyl-m-toluate; Z-pentenyl-m-toluate; 2-isopentenyl-m-toluate; hydroxyethyl-m-toluate; 3-hydroxy-n-propyl-m-toluate; 4-hydroxy-n-butyl-m-toluate; 2-hydroxy-n-butyl-m-toluate; 3-hydroxy-i-butyl-m-toluate; Z-hydroxy-n-pentyl-m-toluate; hydroxyneopentyl-m-toluate; methyl m-ethylbenzoate;

ethyl m-ethylbenzoate; n-propyl-m-ethylbenzoate;

n-butyl m-ethylbenzoate;

isobutyl m-ethylbenzoate;

t-butyl m-ethylbenzoate;

n-pentyl m-ethylbenzoate; isopentyl m-ethylbenzoate; neopentyl m-ethylenzoate;

vinyl m-ethylbenzoate;

allyl m-ethylbenzoate; 2-isobutenyl m ethylbenzoate; 2-isopentenyl-m-ethylbenzoate; 2-pentenyl rn-ethylbenzoate; hydroxyethyl m-ethylbenzoate; hydroxy-t-butyl m-ethylbenzoate; hydroxyisopentenyl m-ethylbenzoate; hydroxyneopentyl m-ethylbenzoate; methyl rn-propylbenzoate;

ethyl m-propylbenzoate;

n-propyl m-propylbenzoate; isopropyl m-propylbenzoate; n-butyl m-propylbenzoate; isobutyl m-propylbenzoate; isopentyl m-propylbenzoate; neopentyl m-propylbenzoate;

vinyl m-propylbenzoate;

allyl m-propylbenzoate;

Z-butenyl m-propylbenzoate; hydroxyethyl m-propylbenzoate; hydroXy-t-butyl m-propylbenzoate; hydroxyneopentyl m-propylbenzoate; methyl m-vinylbenzoate;

ethyl m-vinylbenzoate;

isopropyl m-vinylbenzoate; isobutyl m-vinyl benzoate;

t-butyl m-vinylbenzoate;

isopentyl m-vinyl benzoate; neopentyl m-vinylbenzoate;

vinyl m-vinylbenzoate;

allyl m-vinylbenzoate; 2-isobutenyl m-vinylbenzoate; 2-isopentenyl m-vinylbenzoate; hydroxy-t-butyl m-vinylbenzoate; hydroxyneopentyl m-vinylbenzoate; methyl m-Z-propenylbenzoate; ethyl m-2-propenylbenzoate; n-propyl m-2-propenylbenzoate; isobutyl m-Z-propenylbenzoate; t-butyl m-2-propenylbenzoate; isopentyl m-2-propenylbenzoate; neopentyl m-2-propenylbenzoate; vinyl m-2-propenylbenzoate; hydroxyethyl rn-2-propenylbenzoate; hydroxy-t-butyl m-2-propenylbenzoate; and hydroxyneopentyl m-2-propenylbenzoate.

The compounds used as selective post-emergence contact crabgrass herbicides in this invention are. readily prepared by the conventional esterifictaion of benzoic acids by appropriate hydroxy compounds. In example, the preferred laboratory method for preparing the desired ester (e.g., isopropyl-m-toluate) is to react an appropriate metasubstituted benzoyl halide (e.g., m-toluyl chloride) with an appropriate alcohol (e.g., isopropyl alcohol) in the presence of an acid acceptor such as triethyl amine, as in the following example:

30.8 g. m-toluyl chloride was added dropwise to a stirred solution of 15.0 g. isopropyl alcohol and 25.0 g. triethyl amine in 300 ml. benzene. The mixture was allowed to stir for 2 days. Filtration to remove the triethyl amine hydrochloride and evaporation of the benzene gave 33.0 g. pure isopropyl-m-toluate.

A particularly suitable embodiment of this invention is the use of an isoalkyl, meta-substituted alkyl benzoate, as for example, isopropyl-m-toluate, that is an embodiment used for illustrating this invention as set forth in the activity shown by such a compound in the results of herbicidal tests set forth in the table following the test description.

Post-emergence herbicide tests The test species propagated for testing are: Crabgrass (Digitaria sanguinalis); Yellow Hoxtail grass (Setaria glauca); Johnson grass (Sorghum halepense); Barnyard grass (Echinochloa crus-galli); Amaranth pigweed (Amaranthus retroflexus); and Turnip Brassica sp.).

Each specie is planted individually in 3 inch plastic pots containing potting soil. They are surface seeded and sprinkled with screened soil in an amount suflicient to cover the seed. Immediately after planting, all pots are watered by sub-irrigation in greenhouse trays.

Planting dates for the post-emergence tests are varied so that all seedlings will reach the desired stage of development simultaneously. The proper stage of seedling development for treatment in the post-emergence tests is as follows:

Grasses: .2" in height Pigweed and turnips: 1 or 2 true leaves visible above cotyledons.

Spray applications are made in a hood containing a movable belt and fixed spray nozzle. For passage through the spray hood, one pot of established plants is placed on the rear half of the flat. Treatments are moved to the greenhouse after spraying. Watering during the observation period is applied only by sub-irrigation.

Compounds are screened at a rate of application equivalent to 8 lbs. actual/ acre in a spray volume of 38 gal/acre. Spray hood constants required to deliver the above volume are as follows:

Belt speed: 2 mph. Airv pressure: adjusted to provide 38 g.p.a. delivery Nozzle tip: 8003B (provides uniform cross-section flat spray) Formulations for spray applications (as used in the compositions for which data is set forth in the table hereinafter) are prepared in 50 ml. volumes with the following components:

(1) 1.24 grams compound (8 lb./acre rate) (2) 49 ml. of acetone as solvent (3) 1 ml. xylene-Atlox 3414.

TAB LE Herbleldal activity (percent effectiveness) of compounds as selective post-emergence contact herbicides Post-emergencc contact (at 8 lbs/acre) activity Grass Broadleaf Ama- Yellow John- B arnranth Crab- Foxtail son yard Pig- Tur- Compound grass grass grass grass Weed nip Isopropyl-rn-toluate- 20 O 20 20 20 Isopropyl-o-toluate 0 0 0 0 50 Isopropyl-p-toluate. 30 0 0 20 0 0 From the data in this table, it will be noted that the alkyl ester of the meta-substituted alkyl benzoic acid (isopropyl-m-toluate) is very selective and narrow ranged in herbicidal activity. Also, it will be noted that the ortho-, and para-substituted alkyl benzoic acids are not effective as selective post-emergence contact crabgrass herbicides. Isopropyl-m-toluate is tolerant of grass other than crabgrass and tolerant of two broadleaf herbs tested when applied post-emergent at a rate of 8 pounds per acre. Against crabgrass, isopropyl-m-toluate when applied as defined above provided 80% control.

The selective control of crabgrass in later spring, summer or fall without affecting other grasses is a desirable feature of a useful herbicide for established lawns and turf. The compounds disclosed for use in this invention may be used in various ways to achieve this selective postemergent contact control of crabgrass. They can be applied per se, as solids or in vaporized form, but are preferably applied as the toxic components in herbicidal compositions of the compound and a carrier. The compositions can be applied as dusts, as liquid sprays or as gaspropelled sprays and can contain, in addition to a carrier, additives such as emulsifying agents, wetting agents, binding agents, gases compressed to the liquid state, odorants, stabilizers and the like. A wide variety of liquid and solid carriers can be used in the herbicidal compositions. Nonlimiting examples of liquid carriers include water; organic solvents such as alcohols, =ketones, amides, and esters; mineral oils such as kersosene, light oils, and medium oils; and vegetable oils such as cottonseed oil. Non-limiting examples of solid carriers include talc, bentonite, diatomaceous earth, pyrophyllite, fullers earth, gypsum, flours derived from cotton seeds and nut shells, and various natural and synthetic clays having a pH not exceeding about 9.5.

The amount of the compounds of this invention utilized in herbicidal compositions will vary rather widely. It depends to some extent upon the type of composition in which the material is being used, the nature of the condition to be controlled, and the method of application (i.e., spraying, dusting, etc.). In the ultimate herbicidal composition, as applied in the field, herbicide concentrations as low as 0.0001 weight percent of the total composition can be used. In general, compositions, as applied, containing about 0.05 weight percent herbicide in either liquid or solid carrier give excellent results. In some cases, however, stronger dosages up to about 10 weight percent may be required.

In practice, herbicidal compositions are usually prepared in the form of concentrates, which are diluted in the field to the concentration desired for application. For example, the concentrate can be a wettable powder containing large amounts of a compound of this invention, a carrier (e.g., attapulgite or other clay), and wetting and dispersing agents. Such a powder can be diluted prior to application, by dispersing it in water to obtain a sprayable suspension containing the concentration of herbicide desired for application. Other concentrates can be solutions that can be later diluted, e.g., with kerosene. Thus, it is within the contemplation of this invention to provide herbicidal compositions containing up to about 80 percent, by weight of the composition, of a herbicidal compound of this invention. Accordingly, depending upon whether it is ready for application or it is in concentrated form, the contemplated herbicidal compositions contain between about 0.0001 percent and about 80 percent, by weight of the composition, of a herbicidal compound of this invention, and a carrier, liquid or solid, as defined hereinbefore.

Although the present invention has been described with preferred embodiments, it is to be understood that modiwherein R is methyl and R is isopropyl.

References Cited UNITED STATES PATENTS 2,394,916 2/ 1946 Jones 7 l--107 3,169,849 2/ 1965 Lemin 71107 3,274,235 9/ 1966 'I-Iennis 71-107 JAMES O. THOMAS, 111., Primary Examiner 

